Yeah, thanks for that, Deyan. I think it is your specificity that made your post so brilliant. You won't get that, so my suggestion is to lay off the posting for a little while until you do.

In regards to OP, consider TABATA type exercises. Mentioned before by Eddie Hardon, the interval training stuff is awesome to see spikes in your cardio.

I hate running. I hate cycling. I love swimming but don't have a pool. In the past 8 weeks I have improved my cardio immensely by doing 2-3 rounds of tabata exercises two to three times per week, plus a ridiculous amount of sparring, groundwork, wrestling, pad rounds, circuit training and more. But tabata is something that is so highly recommended it isn't even funny. It hurts if you're doing it right. Apparently it raises your VO2 max, though I am no rocket surgeon to tell you what that means. All I know is that I took 9 minutes off my 21 down burpees test in a month and my cardio recovery is pretty fucking good.

Tabata is one regime for HIIT (high intensity interval training). There are others. They are good for rapid gains in VO2Max compared to steady state exercise but that is only one component of cardio fitness. V02Max is basically your max oxygen uptake, For runners and other endurance athletes we also need to improve V02subMax which is efficiency and lactate threshold, not sure how HIIT protocols work for those. Certainly as runners we do interval training, but there's also tempo runs which are essentially sustained activity at the lactate threshold plus a lot of steady state easy running which we consider to be building base fitness.

Cross-fit type training is top notch.
Basically the warmup/fitness part of fighting sports extended to a full training session is great.
The use of your basic body weight exercises and some weight lifting drills strung together into a long "super-set" that will last a few minutes, is a great way to simulate the strain of a fight.
Though i wouldn't neglect medium length jogs and\or biking swimming.
So, (IMO) for a general top condition cardio, a mix of traditional old fashion training consisting of long runs etc. With cross-fit type training is your winning formula.
But...it was said here before , if you want to improve your cardio for boxing class for example, do boxing specific exercises mainly.

Cardio is a balancing act. To reach your peak, you need to combine a rigorous workout routine, while balancing recovery and mitigating impact injury. A lot of Ironman competitors do this naturally by combining running, biking and swimming. I am a huge fan of the pool because it's about as low-impact an exercise as you can get, but if your goal is to be a runner, eventually you'll have to pound some pavement.

You'll want to combine some muscle confusion activities (hills/uneven ground) with some HIIT training (Tabata is the new "it-workout" for this). I don't think you'll need the long-distance runner's "pacing" workout. Most of that is designed to learn to run an even pace through a race -- if you need a 60s split on your mile time so you run a 4min mile, you need to be able to produce that 60s split darn near exactly. If you're running a 5-10k, you may run 1k splits of 2:45-3min to run around a 15min 5k, or 30min for a 10k (very competitive times -- don't expect to touch these times if you're not already a hardcore runner).

But you will want some long endurance workouts as well. You can get your body in shape to run 15-20 miles, but until you actually do it, you have no idea the uphill battle you're in for. The shorter workouts will get your lungs in shape, but you'll also need the muscle endurance to push out these longer workouts/races (depending on your goal). I think I saw somebody mention lactic buildup.. that kicks in real hard here.

Two things burn in this process: lungs and legs. This is a balancing act as you progress.

If your lungs are burning, but your legs aren't, do more HIIT.

If your legs are burning, but your lungs aren't, do more long distance endurance training.

As the two balance out, continue to push. Usually, they'll start to desynchronize over time. When that happens, use the above to get yourself back in sync.